Production of ethers



April 16, 1940 H. G. SCHNEIDER 2,197,023

BBODUCTION 0F ETHERS Filed Nov. 7, 1956 P02/Fl .2

O1. s FINE GA s /NL L' T ..55 PA n ATO?.

ON FLuonl'a v GAS GsNsnAv-om EVAPORA T02 Patented Apr. 16, 1940 UNITEDlSTATES 2,191,023 PRODUCTION or Ernans Helmuth G. Schneider, Roselle, N.J., assignor to Standard Oil Development Company, a cor-v poration ofDelaware Application November 7, 1036, Serial No. 109,649

15 Claims. I (Cl. 260--614)` A above, in which case the -secondaryolenes are This invention relates to the production of organic compoundsbelonging to the general class of ethers and more particularly to theproduction of such ethers by the directreacton of .ole-

nes with aliphatic hydroxy compounds.l

This application is a continuation-in-part of' my application Serial No.669,147 led May 3, 1933, now Patent 2,065,540, which disclosed broadlythe production of organic compounds, such as ethers, esters, etc., bythe direct reaction of olefines with oxygenated4 organic compounds, suchas alcohols, organic acids, etc., in the presence of -a motivatingagent.

According to 'the present invention, a ldirect etherication of an olefmewith an aliphatic hydroxy compound, such as anv alcohol, is caused totake place at relatively low temperature in the presence of a motivatingagent of the boron flun oride type. 'I'he reaction inthis case, using a20 tertiary oleiine, may be represented by the following equation:

The. alcohol may be regarded as splitting in the course of the reaction,thehydrogen of the hydroxyl group combining with one of the carbons inthe double bond of the oleflne and the rest of 3H the alcohol combiningwith the carbon at the other side of the double bond in the olene. Thusa simultaneous etherication and saturation of the olene is accomplishedwith the resulting production of a Vbranched ether.

. The branched ethers formed find particular adaptation as Aananti-knock blending agent according to co-pending application of HyymlE.` Buc, Serial No. 648,211, filed December 21, 1932, now Patent2,046,243. They may also be used as solvents, etc.

4() Furthermore, this reaction of an alcohol solution of BF3 withtertiary olefines may be used as a convenient method of separatingtertiary olerines from other olenes. For instance, if the 4- oleiinicgases available in a petroleum renery sorption with sulfuric acid, thetroublesome tertiary olefines may first be removed by scrubbing with asolution of boron fluoride in an alcohol.

Such a treatment of the unsaturated gas leaves the primary and secondaryolenes unchanged. A similar separation of vsecondary and tertiary olenescan also be accomplished by treating the mixture with boron fluoridedissolved in an organic acid according to the method mentioned are usedin the manufacturey of, alcohols by abthe ones reacted upon.

When boron fluoride is dissolved in methyl alcohola molecular complex isapparently formed, containing the two constituents in equimolecularproportions even though-an excess of the alcohol is used. In some cases,the motivating agent forms addition compounds with the product and insuch cases these addition compounds may be A decomposed in any suitablemanner in order to liberate the motivating agent, for instance, byhydrolysis with water or caustic soda solution, by distillation, etc. l

'I'he invention may be carried out in a number of different ways but ithas been found particularly convenient to dissolve the motivating agent,such as Aboron iluoride, in the alcohol or other liquid aliphatichydroxy compound and then to agitate this solution with the olene to betreated, or this preferably is done in a countercurrent system, as in atower.

With a gaseous oleflne this may be conveniently and continuously carriedout by the use of a column as shown in the accompanying schematicdrawing which is one illustration of the .entire process for preparingethers, beginning with the manufacture of boron fluoride.

Referring to the drawing, numeral II is any convenient boron fluoridegas generator in which suitable raw materials such as sulfuric acid,calcium fluoride and boric acid or sodium borate are mixed and heated.The boron fluoride evolved is then puried in a suitable apparatus suchas 2 and then is fed in at the bottom of a vertical tower 3 containingfiller bodies over which methyl alcohol is allowed to trickle.. Theboron fluoride dissolves in the alcohol and the solution is collected atthe bottom and conveyed to the top of a second tower` 4 likewisecontaining filler bodies over which-the alcohol-BF: is allowed totrickle downwardly. A suitable olene gas is fed in at the bottom of thistower thereby reacting with the descending solution of alcohol-BE? andproducing an' ether-BF; solution `in excess alcohol. Tower 4 is equippedwith suitable temperature control apparatus, especially for cooling. Theether-BF; solution in alcohol is passed 'into the base of tower 5, intowhich a caustic soda solution is fed in at 4the top by line 5a andallowed Ito gravitate downward countercurrent to the ascending ether-BFasolution in alcohol whichhas a lighter gravity. After hydrolysis, theproducts' from -tower 5 are passed into separator 6' where two layerslare formed, the upper layer vconsisting chiefly of ether and alcoholtilled oi in any order desired, the alcohol .w

arcanes while the lower layer con berate, tercurrently with thatVreaction the ester now' sodium boronuoride and any excess caustic sodawhich may have .been used. The upper ether layer is drawn on from thisseparator and is thm conveyed to suitable iractionating towers 'l and 8where the ether andresidual alcohol are disrecycled. Any residual waterfrom 8 may be wastedpr may be evaporated it it contains appreciablequantities of solids.

The lower layer from separator t is passed into suitable stills il and lto strip on any dissolved ether and alcohf and the residual aqueoussolunon is concentrated or evaporated to dryness in suitable apparatusti, the residue from which may be used to regenerate BFa if desired.

'Ihe pressure in the various units or in the' system as a whole may beregulated at will by suitable control valves.

If liquid olenes are used .instead of an oleflne gas, the reaction maybe carried out in a similar manner by countercurrently contacting thelighter olene liquid with the heavier alcohol liquid containingdissolved BFa.

If desired, a combination process may be used for preparing both theethers and esters in which case the ester-BF2; solution is i'lrstprepared by dissolving BF3 in an acid and treating the solution with asecondary olelne and then treating with the desired alcohol. The lattercauses theA liberation of the ester with simultaneousforma-- tion of analcohol-BFa solution'which is then further treated with a tertiaryolefine to form the ether-BFa solution and then hydrolyzed to liberatethe ether. i

Another method of manufacture is to pass the gaseous motivating agentthrough a mixture of the alcohol and oleiine while agitating the same. Astill further alternative is to mix the motivating agent and oleiine(both in gaseous form) and pass the mixture into the alcohol. In thiscase, however, care must be taken to prevent the polymerization of theolei'lne instead of the desired reaction. This may be done by eitherkeeping the temperature sumciently low or else by diluting with an inertgas in suflicient quantity..

A still further interesting and alternative procedure may be used fortreating an olefine mixture containing both secondary and tertiary olefines. For example, the stabilizer bottoms available in a petroleumreiinery are first reacted with an organic acid-BF: solution prepared asdescribed above and then-mixed with a suitable hydrocarbon solvent suchas a white petroleum oil ldistillate having an A. P. I. gravity betweenabout 45 to 48 and a boiling range between 150 and 200 C. if desired,although this sol-5 is then mixed with an alcohol and fed into the topof a suitable reaction tower Vwhile the bottom layer, the ester-BF:solution, is fed into the bottom of this same reaction tower. Bycountercurrent mixing, a double reaction takes place. The BFs isliberated from the ester-BFa solution and eiects a reaction between thealcohol-and the tertiary oleflne, resulting in the production` of anether-BF: solution dissolved in the excess alcohol. This solution may berecovered as a bottom layer in a suitable settling tank. Counliberatedfrom the ester-BF: solution dissolves in the hydrocarbon solvent and maybe recovered as the upper layer in the separating tank. The ester mayberecovered from the solvent by distillation and the ether may berecovered from the ether-BFa solution by the. methods previouslydescribed.

- In this double reaction procedurejust described it is observed thatthe alcohol and tertiary olene are caused to react by an ester-BF:solution or complex. In other words, in reactions of the type involvedin the present invention the inotivatingsagent may not only be a halideof the boron uoride type alone but may be a molecular complex of such acompound in conjunction with another compound such as the ester referredto above in the ester-BFa complex.`

Furthermore, instead of using boron uorides as the motivating agent,other halides of the boron uoride type may be used such as titaniumtetrachloride, silicon uorides and others. Motivating agents of thistype are adapted to react at low temperatures and to cause the directveste'riilca.- tion and other such reactions also at low temperature,thereby substantially avoiding simultaneous -polymerization of theoleiine.

The present invention is distinctly different from ethericationprocesses involving the use of sulfuric acid or aluminum chloridebecause sulfuric acid is a condensing agent of an entirely differenttype which operates by a different chemical reaction mechanism and, onthe other hand.

aluminum chloride, although being a halide like boron uoride, workssubstantially diii'e'rently. For example, boron iiuoride is operative atsubstantially lower temperatures than aluminum chloride and also BF;will actually cause reactions to take place which will not occur at. allwith aluminum chloride. For instance, in pre- .cation, boron fluoridecaused pentene-2 to react with acetic acid at room temperature toproduce amyl acetate, whereas aluminum chloride could not be made toelect'the same reaction.-

As the reactions areusually exothermic, cooling is generally required tokeep the temperature sufllciently low. The temperature and pressure tobe usedwill depend to a large' extenton/ the particular raw materialsbeing treated. ,However, it is usualy desirable to keep the temper.-

' ature relatively lowthat is, between the approximate limits of C. and100 C., preferably at room temperature, andmost reactions can be carriedout satisfactorily at atmospheric' pressure although if it is desired tospeed up the reactions or to operate in the liquid phase.super-atmospheric pressure" may be used. The reaction involved is almostquantitative on the basis of the motivating agent used.

This invention is applicable to both lower and higher members o! theoletine series. The unsaturation need not occur in open chain aliphatichydrocarbons but may be part cfa ring or cyclic compound such ascyclohexene. Also. instead of using single olenne hydrocarbons. mixturesof such pure compounds or mixtures o! unsaturated hydrocarbons andsaturated hydrocarbons such as occur in petroleum products eithernaturally or as a result of various'reiining, cracking, or othertreating processes, or any other unsaturated hydrocarbon productresultingl from any other Vindustrial process may be used.

Although olenes are'included broadlywithin the scope of this inventionfor the preparation of et paring esters as claimed in my originalappliethers, it is preferred to use tertiary oleiines paralso higherones such as butyl, amyl, decyl, and

even higher mono-hydroxy aliphatic alcohols, as well as variousdi-hydroxy and other poly-hydroxy alcohols, such as ethylene glycol,propylene glycol, glycerol, and alsohigher molecular weight aliphaticpoly-hydroxy compounds of the carbohydrate type including sugars,cotton, cellulose,

etc.

Generally, less than the saturation amountof boron fluoride in thealcohol should be used, because if much larger proportions of boronfluoride are used there is` a tendency to cause polymerization of thetertiary oleilne in preferenceI to ether formation. Preferably not morethan 1 mol of Blzxl per mol of alcohol should be used, and no matter howlarge an excess of alcohol or olefine is used, 1 molof BF2. will give 1mol oi' ether. The mostemcient manner of utilizing the reaction is totreat the olene with a slight excess of the alcohol-Blas reagent.

Under some circumstances, it is desirable to carry out the reaction inthe presence of an inert solvent, for example, when using normally solidaliphatic hydroxy compounds such as the carbohydrates referred to above,as well as when using some of the higher viscous liquidi or solidoleilnes. Suitable solvents include petroleum hydrocarbons,particularlyl saturated aliphatic hydrocarbons, as well as other classesoi.' chemical compounds such as aliphaticethers, for instance, ethylether, isopropyl ether, and the like.

Generally, the reaction should be carried out Iaow about 100 o. andpreferably be1ow 50 c.

and under some circumstances may be carried out as low as -20 or 50 C.,although ordinarily, from the point of view of convenience and economy,ordinary room temperature is satisfactory, making provision for heatingthe reaction slightly to initiate it, ii necessary, and also withprovision for cooling the reaction mass if the temperature risesexcessively.

Although the reaction may ordinarily be carried out at atmosphericpressure, it may be desirable at times to use super-atmospheric pressureup to 10 or 20 atmospheres, for instance, lfor eecting an acceleratedreaction or for carrying out areaction with normally volatile materialsor in the presence of a liqueiied normally gaseous solvent such asliquefied propane and the like.

The following examples are given for the pur pose of illustration only:

Example 1 A cc. sample of a solution of 55u-grams of boron fluoride in100 ccs. of methyl alcohol was reacted with 70 ccs. of trimethylethylene at room temperature for 240 minutes. ccs. of the productboiling at -85 C. were obtained. On purification this proved to bemethyl tertiary amyl ether (B. P. 86 C.).

Example `2 about room temperature.

42 ccs. of a product boiling about 80-87 C. was obtained. This productwas 'identified as above to` be methyl tertiary amyl ether afterpurification.

Eample 3 38 ccs. of the methyl alcohol-BFE; solution prepared in Example2 were reacted with 21.5 grams of isobutylene at room temperature. As aresult, 45 ccs. of ether product was obtained, the etherl in this casebeing methyltertiary butyl ether (B. P. 55.3 C.)

It is not desired to be limited by the foregoing examples or theories ofthe operation of the invention but by the following claims in which itis my intention to claim all novelty inherent in the invention asbroadly as the prior art I claim:

1. The process of preparing ethers which comprises reacting an aliphaticalcohol with a terltiary oleilne at a temperaturebelow about C.

in the presence of a normally gaseous and liquid halide of an inorganicmetal oi groups III and IV of the periodic system. ,i

2. Process according to claim 1 in which the halide used is selectedfrom the group consisting of boron iiuoride, organic complexes of boroniluoride, titanium tetrachloride and silicon fluoride. v

3. 'Process according to claim 1 in which boron iiuoride is used asmotivating agent.

4. Process according to claim 1 in which the aliphaticv hydroxycompounds used contain at least one primary hydroxy group.

5. Process according to claim 1 in which lower aliphatic primaryalcohols are used.

6. Process according to claim 1 in which an aliphatic poly-hydroxyalcohol is used.

7. Process according to. claim 1 in which tertiary oleilnes are used.

8. Process `according to claim 1 carried out at a temperature belowabout 100 C.

9. Process according to claim'l carried out at 10. The process ofpreparing ethers which vcomprises reacting aliphatic primary alcoholswith tertiary oletlnes in the presence of boron fluoride at atemperature not substantially'above room temperature.

` 1l. The processl oi preparing ethers, which` comprises reacting analiphatic primary monohydroxy alcohol with a tertiary oleiineat adaemperature below 100 C. in the presence of boron fluoride.

12. Process according to claim4 11 in which an excess of the alcohol isused over that required for etheriilcation with theoleilne.

13. Process accordingl to claim 11 in which the amount of boron iiuorldeused is less than the amount required to saturate the alcohol used.

14. The process of preparing ethers, which comprises dissolving boronfluoride inA an aliphatic primary mono-hydroxy alcohol -having not morethan 10 carbon atoms, the amount of boron fluoride used beinginsuilicient to saturate said alcohol, and then contacting said solutionl' with a. tertiary olene at a temperature below 15. The process o fpreparing mixed methyl ethers, which comprises reacting methyl alcoholwith a tertiary oleiine at a temperature below 100 C. in the presence ofboron fluoride.y

' 1 HEIMUTH G. SCHNEIDER.

